CN113976824B - Method for preventing mixed crystals from being generated at free end of conjuncted single crystal guide blade core - Google Patents
Method for preventing mixed crystals from being generated at free end of conjuncted single crystal guide blade core Download PDFInfo
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- CN113976824B CN113976824B CN202111220787.9A CN202111220787A CN113976824B CN 113976824 B CN113976824 B CN 113976824B CN 202111220787 A CN202111220787 A CN 202111220787A CN 113976824 B CN113976824 B CN 113976824B
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- core
- free end
- blade
- wax
- single crystal
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C7/00—Patterns; Manufacture thereof so far as not provided for in other classes
- B22C7/02—Lost patterns
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
- B22C9/04—Use of lost patterns
- B22C9/043—Removing the consumable pattern
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/22—Moulds for peculiarly-shaped castings
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/52—Alloys
Abstract
The invention belongs to the field of investment casting single crystal blades, and particularly relates to a method for preventing mixed crystals from being generated at the free end of a conjuncted single crystal guide blade core. The technical scheme of the invention is as follows: a method for preventing the free end of the core of conjuncted single crystal guide vane from generating mixed crystal, in the course of preparing wax mould, set up and draw the triangular wax sheet patch of crystal in the free end of core, dewax and form the alloy liquid runner between side end surfaces of small edge plate of core and blade after dewaxing. The method for preventing the mixed crystal from being generated at the free end of the core of the conjuncted single crystal guide vane solves the problem of mixed crystal of the flange plate caused by coating the free end of the wax brushing core of the conjuncted single crystal guide vane, and improves the qualification rate of the conjuncted single crystal guide vane.
Description
Technical Field
The invention belongs to the field of investment casting single crystal blades, and particularly relates to a method for preventing mixed crystals from being generated at the free end of a conjuncted single crystal guide blade core.
Background
The conjuncted single crystal guide vane for aero-engine is mostly in I-shaped structure with a certain angle between the vane body and the flange plate. The preparation process of conjuncted single crystal guide vane mainly adopts investment precision casting at present, namely we generally call lost wax method, the module formed by the vane wax mould is coated with coating and sand, the mould shell is formed after drying and hardening, then the ceramic mould shell in the shape of vane cavity is formed after dewaxing and roasting, and the conjuncted single crystal guide vane is formed after casting alloy liquid and directional crystal pulling. The blade interior cavity of a hollow guide blade is usually formed by a ceramic core. In order to avoid cracking of the core due to different shrinkage and expansion degrees between the core and the shell at a high temperature, two ends of the core are usually respectively set as a fixed end and a free end. The fixed end is used for ensuring that the core does not shift and swing during the process of filling molten metal into the shell. The free end is used for avoiding cracking of the weak position of the core caused by the shrinkage of the shell when the core is subjected to secondary sintering in the high-temperature crystal pulling process. The free end is usually provided by brushing wax, so that a gap with equivalent brushing wax thickness is formed after dewaxing and roasting of the shell, and a certain clearance is reserved for the core. But at the same time this also results in filling the gap during the casting of the alloy. Along with the gradual descending of the mould shell to a cold zone in the directional crystal pulling process, the alloy liquid is formed to solidify sequentially from bottom to top, the thin-wall bulge position at the free end can generate transverse heat radiation at first when approaching to the cold zone, and the single longitudinal temperature gradient of the single crystal blade in the crystal pulling process is destroyed by the solidification when reaching the nucleation supercooling degree prematurely, so that the small edge plate of the blade generates crystal grains with different orientations with the single crystal at the blade body part, namely the impurity crystal, the integrity of the single crystal of the blade is not in accordance with the standard requirement, the rejection rate of the blade is higher, and the manufacturing cost of the blade is increased.
Disclosure of Invention
The invention provides a method for preventing mixed crystals from being generated at the free end of a core of a conjuncted single crystal guide blade, which solves the problem of mixed crystals of a flange plate caused by coating the free end of the wax brushing core of the conjuncted single crystal guide blade, and improves the qualification rate of the conjuncted single crystal guide blade.
The technical scheme of the invention is as follows:
a method for preventing the free end of the core of conjuncted single crystal guide vane from generating mixed crystal, in the course of preparing wax mould, set up and draw the triangular wax sheet patch of crystal in the free end of core, dewax and form the alloy liquid runner between side end surfaces of small edge plate of core and blade after dewaxing.
Further, the method for preventing the free end of the conjuncted single crystal guide vane core from generating mixed crystals specifically comprises the following steps:
step one, a free end and a fixed end of a mold core are of cuboid structures, one side of a small blade edge plate is the free end of the mold core, one side of a large blade edge plate is the fixed end of the mold core, and the fixed end of the mold core is provided with a groove;
step two, brushing wax on the surface of the free end of the core when the wax mould is trimmed, and positioning the geometric center setting points of the free end surfaces of the core;
step three, arranging a seeding triangle wax sheet patch at the lowest point of the free end of the core along the vertical downward direction;
and step four, manufacturing a molded shell, and forming an alloy liquid flow passage between the free end of the mold core and the side end surface of the small edge plate of the blade after dewaxing.
The beneficial effects of the invention are as follows: according to the method, in the preparation process of the wax mould, the seeding triangle wax sheet patch is arranged at the free end of the mould core, and an alloy liquid flow channel between the free end of the mould core and the side end face of the blade small flange plate is formed after dewaxing. When the alloy liquid is filled into the alloy liquid flow channel, a longitudinal heat conduction path is given to the protruding part for transverse heat dissipation, the free end is kept along the single heat flow direction of the triangular plate, the free end is formed to be sequentially solidified from bottom to top, and abnormal nucleation of the outer edge of the protruding part due to supercooling is avoided, so that the single crystal integrity of the blade is damaged. Meanwhile, a crystal seeding mode of triangular plate patch is adopted, the wax mould trimming operation is simple and convenient, the shell coating is easy to dry, and the casting trimming is relatively easy, so that the method is suitable for large-scale production of single crystal blades.
Drawings
FIG. 1 is a schematic illustration of a conjoined single crystal guide vane; in the figure: 1 is a blade body I, 2 is a blade body II, 3 is a blade small edge plate, 4 is a blade large edge plate, 5 is a blade body I inner cavity, and 6 is a blade body II inner cavity;
FIG. 2 is a schematic illustration of a core structure;
fig. 3 is a schematic view showing the installation state of the seeding triangle wax sheet.
Detailed Description
As shown in fig. 1-3, a method for preventing the free end of a joined single crystal guide vane insert from producing foreign crystals comprises the steps of:
step one, a mold core free end 7 and a mold core fixed end 8 are of cuboid structures, one side of a small blade edge plate 3 is provided with the mold core free end 7, one side of a large blade edge plate 4 is provided with the mold core fixed end 8, and the mold core fixed end 8 is provided with a groove 10; the rectangular cross section of the core fixing end 8 is set according to the size of the outlet cross section of the blade body one inner cavity 5 and the blade body two inner cavity 6 near one side of the blade large flange plate 4, preferably, the rectangular cross section of the core fixing end 8 is inscribed in the outlet cross section of the inner cavity at one side of the blade large flange plate 4, and the length of the core fixing end 8 extending out of the blade body is 30-40 mm; the groove 10 is rectangular, the distance between the edge of the groove and the edge of the ceramic core fixing end 8 is more than 5mm, and the depth of the groove is not more than 1/3 of the thickness of the whole ceramic core fixing end 8; the rectangular cross section of the free end 7 of the ceramic core is arranged according to the size of the outlet cross section of the blade body I inner cavity 5 and the blade body II inner cavity 6 of the blade near the side of the blade small flange plate 3, the rectangular cross section of the free end 7 of the core is inscribed in the outlet cross section of the inner cavity of the side of the blade small flange plate 3, and the length of the free end 7 of the core extending out of the blade body is 15-20 mm;
step two, when the wax mould is trimmed, the surface of the free end 7 of the mould core is brushed, the thickness is 0.5mm, point positioning 11 is arranged at the geometric center of each surface of the free end 7 of the mould core, namely, pits are buckled at the geometric center positions of each surface, the depth is 2mm to the surface of the ceramic mould core, methyl blue is coated at the point positioning 11 position, and the coating thickness is 0.1mm;
thirdly, setting a seeding triangular wax sheet 9 for repairing at the lowest point of the free end 7 of the mold core along the vertical downward direction (namely the vertical crystal pulling direction) by using bonding wax; the included angles at the bottoms of the patches of the seeding triangular wax plates 9 are all set to be 30 degrees, the outer sides of the patches of the seeding triangular wax plates 9 are flush with the outer sides of the free ends 7 of the cores, and the thickness is 2mm; the positions of the complementary of the seeding triangular wax sheet 9 and the connection position of the blade wax mould are transited in a wax brushing mode, so that smooth transition is ensured, and the size R of a transition fillet is 1-1.5mm;
and step four, manufacturing a molded shell, and forming an alloy liquid flow passage between the free end 7 of the mold core and the side end surface of the small blade edge plate 3 after dewaxing.
Claims (1)
1. A method for preventing the free end of the core of a conjuncted single crystal guide vane from generating mixed crystals is characterized in that in the preparation process of a wax mould, a seeding triangle wax sheet is arranged at the free end of the core for repairing, and an alloy liquid flow channel between the free end of the core and the side end face of a small edge plate of the vane is formed after dewaxing; the method specifically comprises the following steps:
step one, a free end and a fixed end of a mold core are of cuboid structures, one side of a small blade edge plate is the free end of the mold core, one side of a large blade edge plate is the fixed end of the mold core, and the fixed end of the mold core is provided with a groove; the rectangular cross section of the core fixing end is arranged according to the size of the outlet cross section of the blade body one inner cavity and the blade body two inner cavities close to one side of the blade large edge plate, the rectangular cross section of the core fixing end is inscribed in the outlet cross section of the inner cavity of one side of the blade large edge plate, and the length of the core fixing end extending out of the blade body is 30-40 mm; the size of the rectangular cross section of the free end of the core is set according to the size of the outlet cross section of the blade body I inner cavity and the blade body II inner cavity close to one side of the blade small flange plate, the rectangular cross section of the free end of the core is inscribed in the outlet cross section of the inner cavity of one side of the blade small flange plate, and the length of the free end of the core extending out of the blade body is 15-20 mm;
step two, brushing wax on the surface of the free end of the core when the wax mould is trimmed, and positioning the geometric center setting points of the free end surfaces of the core;
step three, arranging a seeding triangle wax sheet patch at the lowest point of the free end of the core along the vertical downward direction; the included angles at the bottoms of the seeding triangle wax sheet patches are all set to be 30 degrees, and the outer sides of the seeding triangle wax sheet patches are flush with the outer sides of the free ends of the cores; the positions of the flip-chip triangular wax patch and the connecting positions of the blade wax patterns are transited in a wax brushing mode, so that smooth transition is ensured;
and fourthly, manufacturing a molded shell, forming an alloy liquid flow channel between the free end of the mold core and the side end surface of the small edge plate of the blade after dewaxing, and providing a longitudinal heat conduction path for a convex part for transverse heat dissipation when the alloy liquid is filled into the alloy liquid flow channel, so that the free end is kept to be sequentially solidified from bottom to top along the single heat flow direction of the triangular plate, and the abnormal nucleation of the outer edge of the convex part due to supercooling is avoided.
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| CN202111220787.9A CN113976824B (en) | 2021-10-20 | 2021-10-20 | Method for preventing mixed crystals from being generated at free end of conjuncted single crystal guide blade core |
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| CN202111220787.9A CN113976824B (en) | 2021-10-20 | 2021-10-20 | Method for preventing mixed crystals from being generated at free end of conjuncted single crystal guide blade core |
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| CN113976824B true CN113976824B (en) | 2023-09-15 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115283650B (en) * | 2022-07-14 | 2024-03-22 | 中国科学院金属研究所 | Method for preventing blade body of single crystal twin cast turbine guide blade from being mixed |
| CN116906126B (en) * | 2023-09-14 | 2023-12-08 | 中国航发北京航空材料研究院 | Multi-body guide vane of ceramic matrix composite and single crystal superalloy and preparation method thereof |
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